[kafka] branch 3.4 updated: KAFKA-14887: FinalizedFeatureChangeListener should not shut down when ZK session expires

[rn...@apache.org]

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rndgstn pushed a commit to branch 3.4
in repository https://gitbox.apache.org/repos/asf/kafka.git


The following commit(s) were added to refs/heads/3.4 by this push:
     new 03b41b54c92 KAFKA-14887: FinalizedFeatureChangeListener should not shut down when ZK session expires
03b41b54c92 is described below

commit 03b41b54c92c128b43221ee4fe6083c11a4e0173
Author: Ron Dagostino <rn...@gmail.com>
AuthorDate: Wed Apr 19 19:45:26 2023 -0400

    KAFKA-14887: FinalizedFeatureChangeListener should not shut down when ZK session expires
    
    FinalizedFeatureChangeListener shuts the broker down when it encounters an issue trying to process feature change
    events. However, it does not distinguish between issues related to feature changes actually failing and other
    exceptions like ZooKeeper session expiration. This introduces the possibility that Zookeeper session expiration
    could cause the broker to shutdown, which is not intended. This patch updates the code to distinguish between
    these two types of exceptions. In the case of something like a ZK session expiration it logs a warning and continues.
    We shutdown the broker only for FeatureCacheUpdateException.
    
    Reviewers: Kamal Chandraprakash <ka...@gmail.com>, Christo Lolov <ch...@gmail.com>, Colin P. McCabe <cm...@apache.org>
---
 .../scala/kafka/server/FinalizedFeatureChangeListener.scala    | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/core/src/main/scala/kafka/server/FinalizedFeatureChangeListener.scala b/core/src/main/scala/kafka/server/FinalizedFeatureChangeListener.scala
index 83e9c149284..b16b3c187ac 100644
--- a/core/src/main/scala/kafka/server/FinalizedFeatureChangeListener.scala
+++ b/core/src/main/scala/kafka/server/FinalizedFeatureChangeListener.scala
@@ -17,7 +17,7 @@
 
 package kafka.server
 
-import kafka.server.metadata.ZkMetadataCache
+import kafka.server.metadata.{FeatureCacheUpdateException, ZkMetadataCache}
 
 import java.util.concurrent.{CountDownLatch, LinkedBlockingQueue, TimeUnit}
 import kafka.utils.{Logging, ShutdownableThread}
@@ -156,10 +156,12 @@ class FinalizedFeatureChangeListener(private val finalizedFeatureCache: ZkMetada
           // safe to ignore the exception if the thread is being shutdown. We raise the exception
           // here again, because, it is ignored by ShutdownableThread if it is shutting down.
           throw ie
-        case e: Exception => {
-          error("Failed to process feature ZK node change event. The broker will eventually exit.", e)
+        case cacheUpdateException: FeatureCacheUpdateException =>
+          error("Failed to process feature ZK node change event. The broker will eventually exit.", cacheUpdateException)
           throw new FatalExitError(1)
-        }
+        case e: Exception =>
+          // do not exit for exceptions unrelated to cache change processing (e.g. ZK session expiration)
+          warn("Unexpected exception in feature ZK node change event processing; will continue processing.", e)
       }
     }
   }